Electric welding tool



Patented June 1, 1943 UNITED STATES PATENT OFFICE ELECTRIC WELDING TOOLApplication April 22, 1944, Serial No. 532,315

12 Claims.

My invention is a, rotary welding device for holding and rotating aboring electrode which may be a fastening device, and which is one oftwo electrodes creating an arc, the other electrode being the work withwhich the boring electrode is fused due to the application to it whilerotating of a suitably controlled electric current, through the mediumof a current collecting system of slip rings and brushes or othersuitable means.

The rotary device, for holding the electrode, may be a self-containedauxiliary chuck, adaptable to present tools, such as a portable electricdrill or nut runner or the like, or it may be adaptable for use in adrill press or lathe, in short, any suitable rotatin machine. It, ofcourse, may be an integral part of and built into any of the abovemachines. In any case, however, the auxiliary chuck, or the toolcontaining the elements of the chuck, will necessarily contain or haveas an adjunct a necessary rotary current collecting system, electric orelectronic controls, conventional holding devices such as snap chucks,screw drivers, etc. which may be magnetic or not, depending upon thecontrols, and the service which they are to be used.

A major difference in my invention over other portable welding tools ofits nature, is the employment of rotary motion, and the inherent abilityof all revolving tools to bore into and through hard or relativelyimpervious materials such as wood, transite, gypsum, or metals, by theuse of suitable boring electrode attachments, held by the rotary machinewhich may be a portable electrode drill; or stationary machine like adrill press or lathe. able welding tool immediately eliminatespredrilling of holes in facing materials like lumber, transite andgypsum, before welding the fastener which holds them in. place, as isnow the necessity among other portable welding tools.

Another major difference in my invention over other portable weldingtools employed to weld a pin or the like to a backing sheet is themethod of creating the are.

, 2 ing device, used to time the duration of the arc, and also toregulate its length. The shape of the spiral lifting cam which isinfinitely variable, used in combination with the rheostat for governing5 the rotary speed of the electrode, constitutes the timing system,which precludes the use of customary timing devices, and utilizes onlythe inherent rotary motion of the tool, which, of course, is notpossible in portable welding tools now in use.

Another type of welding tool depends on creating an are by coating theend of the pin or electrode to be welded in place with filings and chipsof metals which fiux when current is applied. By the use of rotarymovement in my invention, I utilize the natural and inherent ability ofmy drill electrode to create chips and filings from and in, the otherelectrode or work when rotating in contact with the work to which it isto be attached, adding nothing, but utilizing the advantage of readilyfusable chips in creating the desired arc.

In another case the arc is formed by holding a sharply pointed electrodeagainst the other electrode or plate and melting oil the tip when servean analogous function in facilitating the proper arc.

Through the option of the use of any desired boring electrode devicewhich comprises a suitable fastening device taking the place of a studon construction Work, my port- 5 bolt, or nail, or the like but which isequipped with the boring end of any suitable type, and composed of anysuitable alloy which is harder than the facing material such as wood,transite, etc. and at least equal in hardness to the otherelectrode orwork, to which it is to be welded as a fastener of the wood, etc., I canbore through the relatively impervious facing material; and thennaturally create metal chips, cuttings and fins, while boring a crater,or if desirable a hole,

The principal mode of operation used in the in the work or otherelectrode. I then app electrode is withdrawn in creating the arc, but isrotated at the same time, with decided advantages to be noted.

As preferably arranged, the raising of the drill electrode away from theother electrode is an intating and welding current and my welding toollifts the boring electrode upward while simultaneously causing it torotate, thereby creating an are by the withdrawal from contact and thefiuxin of the chips and/or fins present between the electrode and baseplate. After suitable timing, the electrode is pushed down to weld it inor onthe base plate.

Through the choice of suitable alloys, and

' tegral part of the function of the mechanical timshapes in the boringdevices, and the choice of suitableiibearin 'lq.

thedevices used or adjustments thereof, I can create in the base plate acrater or metal mold of any desirable depth, thereafter proceeding withthe same sequence of operation as previous- 'ly described, thusachieving complete control over penetration and therefore fusion, ofweld metal into the base metal, which is the most importantcconsideration in the;.-strength of a-weljd.

By the use as an "electrode of the drill 'or "boring tool whichpenetrates paint, scale and surface impurities, a good clean electricalcontact between electrode and work is assured. --;.G-ontrolled depth ofpenetration of the drill type electrode into the work can 'be 'obtainedby simple adjustment, and a featuremf-my-"practice is that it creates,if desirable, a metal mold in the base plate by the rotary actipn-zofthe electrode. Indeed the regulation of timing and lineal length of thepreviously formed arc, "and the simultaneous rotary motion of theelectrode, caused by the liftingractionrofzthelweldingidevice creates aeonditionan'alogous tocentrifugal casting -accompanied l by the :outward:rotary disposition o'f the non metaliic gaseszand 'Limpurities-'-genera-ted in -the weldin zzone.

din interesting and valuable system ;-is used :;if =desirab1e andpossible with 'amy stool. It :iszthe housing oron or' fasteriin :of, :as-integral ipart -of the tool, the -re'turn f circuit,inam'ely a1properly insulated pole or leg, adjustable for length eas shown on thedrawing, -so" that ith'e vamount of travebof'the current through thework isiatia niiriimum. I'liis-makes the voltage dropfic'onstant andcutting costs insome cases,-:overcomes :the

inability to get a good :returnpircuit such has 811 "countered 'in -asuspended ceiling, ;through the work. "The ca bles-are coaxial inithiscease and wherefore save the pperator ithe time of teenstantly changinghis circuit connections.

- I have illustrated :my invention in a selected -'-e1ribo'diment whichis depicted in the :drawings and will be described. The inventioninherent in' this example and other equivalent embodime'nts of any"invention* will' be' set forth in the claimsappended-hereto, to whichreference z-is herby made.

*Inthe drawings:

l igure 1 is avertical section partially: diagrammati'cthrough aportablestool. according 170 any invention.

Figure 2 is a detail illustrating an l-alternative arrangement totheilift-ing 'andatiming: cam-shown in Figure L parts, thecasing:portion 7 I ,:at the upperend of which the housing "portion 2 inwhichrheostatiindicated:diagrammaticallyat Z3,lInathis-zupper.housingiportionds alsormounted' the dou'ble :throwcontrol switch which is ep- 'eratel:l l byia finger "piece f l a-titheigi'ip ;portion :of

' thisrhousing. 'EIn ithe casing portion; Lisilocatedianoeliectric'rmotori i withsan ofisetzxirive consisting Tdf- 'pi'ni0ngear' lcandistubril :supportedi in: a

"i'I'heilowereendrof .t'heistnb shaftirli is hollow -and '"irhi-s .upper:end as :inrlieate'daat EZe-issmal-lenthan the rest of the tool shaft,and is equipped with a slot 63 near its upper end which is traversed bya driving pin I l, preferably of dielectric material or faced therewith,which pin is held in the lower end of the hollow portion of the stubshaft. A disk of insulation material as at I5, is mounted near the upperend of the main portion of the rtoolfshaftyand a spring it surrounds theupper -"end of thetool'shaft and bearspn a shoulder Ii 10 developed onthe lower end of the stub shaft. "This structure is provided so that thestub shaft ,drives-thmtool shaft, but the tool shaft may rise by slidingover the driving pin and telescoping into theestub shaft. Any othersuitable mecha- =m-nism which5permits of proper insulation for the *tool'shaft can be used for the indicated pur- 1 410578.

The 1OWe1 portion I8 of the casing provides a bea'ring H? for the upperend of the tool shaft, and a bearing 20 for the lower end thereof.iMountedzonlpads ,2! within this casing-suitably insulated'therefrom'asby mounting plates 22, :are :t-woiresilient electric contacts :23,independ :entlyz:connectediin:v one circuit Of'Ithe control our- 5mm.1Located1on1the tool sshaft isiadisk of in- ;sulation-,:2a marryingzaxcopper ring '24, which rw hen;:;the itookshaf-t ,is :in its :upperposition will -:establish :nontact between the contacts or terminalse23.

LQcated-:.on theitoolshaft 'H is a ea-m collar #5. 'solenoid"26,'.;thearmature-2i of which-proziects zintoya :spring retaining Th0usingi28,includes rspring ifl, svhich actszasa tension spring to scholdithearmature outwardly. Theinner end of itherarmature is directed:toward theaxis of the .ztof l shaft H ;.in;such a position that when the :solenoid5 26 is energized thearmature is thrust zastoward-zlthe cam collaniinsucha position that its tenid willzri'deund'er the:lowportion of thecam. 4U T-he :armature also carries an abutment which will rcloseg-andlmaintain LCIOSGd :a small spring WitCh#21A.WhiGh, as will thencted,zcompletes the :nonnections for: welding current application'tothe i-"tool'shaft.

The tool shaft has a wide coppersring -2Szthere on-.against :WhiCh 5'rests ;,a usual :type of carbon brushfl 8A, througllawhich' weldingcurrent is appliedzto the toolrshaft.

Y The, lower end ,of the .toolshaft Where it proa -5o iects fromthewcasingmortion "l8 has a, suitable huok arrangement ":Wh'iCh willpreferably he of =material- -whichdoes not fuse :to theelectrode.smember. i;In-.-.Eig-ure 3 I have illustrated a chuck :of; atype-,whichrhasaythreaded stem -29 that ascrews -into the-endofthe toolshaft and a-bcdy lformedof two hollow sections 30 and Si, both 10f:whichare internally threaded, the member 1 3 ll .ireceivingithe stem.The two halves are hinged together by=means of hinge pins 32 (Figures)so thatloneof :the sections will swing away from ethebther, but whenthe-two sections are closed 1- agains teachsot-her, a-threaded bore willbe l rerbsented @into which the electrode is screwed so that its endrests against the-end Of .the'stem $29. eA ring :3'3rwhich is: dropped:over the assembly :or, ra-ised' away therefrom, serves to hold it{closed .during:use,:and to quickly-and completely erelea-se theelectrode after it has been welded in.place. 1'70 :I-fhe casing:p 1.ti0n19s "is equipped with-a serries inf projecting aposts 36 which areinternally threaded to receive spacing screws :35. Also a-T:brackti3.6ronathe casing portion i8 .is used, where cthe work:permits :for -;mo.unting i-aadiustably a flo-ssleeveifil, which is. aspring :pressed plunger The sleeve is connected to one end of thewelding current circuit, the other end of which is connected to thecarbon brush holder. The plunger 38 may thus be used to establishcontact with the work close to the welding point.

As so arranged, the electric wiring and control are such that theoperator proceeds preferably as follows: First placing an electrode inthe chuck, the operator swings the double throw switch to apply currentto the motor which is then used to drill or screw the electrode throughfacing material into the work. The electrode as illustrated moreparticularly in Figure 3 has a threaded body 39 or a body otherwisesuitably shaped for chucking on the tool shaft, a fluted portion All, inwhich chips and metal particles will lie or be removed from the holewhen the electrode is inserted in the work, and a bit type end portion4| slight- 1y larger, preferably, than the shank. This, of course, isonly one type of suitable electrode.

The motor operation will result in causing the electrode to drill itsway through a sheet of material, such as wood or transite, to beattached to a base member. and then will start to drill away and enterthe other electrode or base member, sheet, beam, frame or what not towhich the drill electrode is to be secured by welding. Such a base sheetis illustrated at 42, and the adjustment of the posts 34 will be suchthat the drilling operation will continue to a suficient extent to forma crater in the base sheet. This may be quite shallow or can bedeveloped into a hole of whatever penetration may be desired. When theadjustment posts have bottomed the drilling operation is stopped bythrowing the double throw switch to neutral.

Then the double throw switch is thrown so as to set up a series ofcircuits, one of which sends current to the motor through the rheostat42, thus obtaining a controlled speed of rotation of the motor. Anothercircuit sends current through the solenoid for the cam engagingarmature. which is thrust toward the cam sleeve on the tool shaft.Another circuit is established which will send current through a relayfor closing the welding current circuit, but this relay will not operateuntil the solenoid for the cam engaging armature has moved far enough toride under the low portion of the cam surface. The motor will berevolving the electrode idly in co tact with the work until thissolenoid armature has moved to home position beneath the cam whereuponthe weld ng current will be applied and the tool shaft will start torise. When the tool shaft has risen through the distance for which thecam was cut, the switch contacts 23 will be connected by the ring 24,whereupon all switches will be opened even though the double throwswitch is held in welding position.

The withdrawal of the electrode will draw an arc. The chips anddrillings will fuse, the electrode will rotate during this action toimpart a centrifugal action to the fusing metal, and form a pool offused metal in the crater or hole in the base sheet. When the cam isreleased by springing back of the solenoid armature. the spring bearingon the tool shaft which opposes its rise will force the shaft downwardlyramming the electrode which will still be rotating slightly due toinertia of the motor, into the crater which was formed, resulting in atight weld.

It may be desirable in certain instances instead of using the tool withan electrode which drills its way into the work, to bore a hole in thework first and introduce the electrode later either with some additionaldrilling or not, and operate the device for drawing the arc, in thedescribed rotary manner, and then hammering the electrode home in thecrater formed for it.

It is noteworthy that the timing of the arc in the use of the tool isperformed by the dimensions and pitch of the cam and also the speed ofoperation of the motor.

This novel timing mechanism has the inherent advantage of always beingconstant under any given set of conditions, for the reason that thedrill electrode has penetrated the paint and rust or scale on the basemetal, thereby achieving an excellent contact for every weld. Thisunusual ability not enjoyed by non-rotating welding tools, immediatelyprecludes time lag encountered in other tools by their inability toguarantee good contact. In addition to this feature, a second safeguardalso guarantees correct timing, and this is the fact that weldingcurrent can only flow, after the lifting pin has engaged the cam.

In ordinary practice after the adjustable abutments 35 have contactedthe work, the spring tension on the shaft which may have been built upduring drilling will continue to rotate the drill point to a definiteposition. However, in order to insure that the tool carrying shaft willalways end its drilling operation at a definite position, I may supplymy tool with a device to prevent endwise movement during drilling. Thismay be done electrically with a solenoid, but I have here shown a fork49, which straddles the shaft ll when pushed inwardly by means of therod ii of which it is the terminus. By bearing on the top of thecollecting ring, this fork will assure a definite position of the shaftduring drilling and it must be withdrawn to start the welding portion ofthe operating cycle.

Instead of a single spiral cam surface, it may be desirable to lift theelectrode further or extend duration of arc in which case the preferredpractice is to employ a structure such is illustrated in Fig. 2. In thisview the tool shaft is equipped with a thread HA, and the solenoidarmature is thrust in to engage the screw.

Referring now to the diagra-m-the double throw switch indicated bynumeral 4 may be thrown to establish contacts M and Ml, to supplyregular driving current to the motor The line connection to the switchis indicated L. The other incoming lead for regular sup ply is indicatedat L-l. Closing of contact M-J will send current through a suitable leadto the solenoid C-!, which solenoid operates a series of switches tobring them to closed position. The first of these is the switch S-!,which when closed contemplates a circuit through t e windings of themotor. The switches S -2 and S3 which are closed by the same solenoid donot have any effect during the drilling portion of the cycle ofoperations. As so far described the double throw switch has set themotor in motion and the drilling is carried on until the proper craterhas been formed the work.

The operator then throws the double pole switch through neutral posit onto the position to make contacts M2 and Bil-22. The contact M3 sendscurrent through the rheostat and through the motor and the switch S-l.thus com leting a circuit for controlled speed driving of the motor. Thecontact l\ i2 sends current through the solenoid 2B, thence back throughthe switch 8-3 and to the return lead Ll.

By establishing contact M--2 current sent through the switch SZ, andthence connects up the circuit to solenoid coil C--3, except for thebreak in, this circuit, which isestablishedby the switch 2-:1A, which;operates assoon' as the -so1enoid thrusts its armature to position: atthe low point-of the cam. Whilethis is taking place the motor starts.its slow revolution. When the switch 21A closes this completes. a.circuit through the coil (2-3, and back to the lead-in 'Ll,, and thecoilthen operates the-welding current switch 8-5..

Welding current then is. applied through the brush 28A, andcollector'ring 2 8, and to-the return electrode 3,8. The motor startslifting the-tool shaft at this point, withdrawing; the electrode fromthebase of its crater,.anddrawing anare, as has been described. Wherethe head of the electrode to be fused with-thework is larger than the.body, there is aspacingbetween the electrode shank or body and the holewhich has been'bored into the-work. The arc jumps through this spacealso. Thisspacealso'actsv as an outlet for'borings in the facingmaterial.

As soon as the contact ring24connects together the contacts 23, currentpasses. from. at-ap on the lead-in line L, shown as near-the. connectionto the double-pole switch, across between the contacts23, and through asolenoid-coilC-fl. and the lead-in L-l.

The switches S,l, 8-2 and 3-3 are ofthe type which when closed by theiroperating coil Ci-.-l, stay closed upon de-energizing, of the coil C-i.But the energizing of the coil C'4, will resultin opening all threeswitches. Thus when the shaft rises: for the distance measured by; thecam, which will bring the contact ring 24 into position of closing thecircuit through coil C4, all current to the apparatus is turned off. Theswitch 8-5 for welding current is a spring opening switch which opens assoon as the coil C'3 is de-energized, hence the welding current isturned 01f with all the rest. The solenoid armature having beenwithdrawn from the cam as soon as the coil 26 is de-energized, the toolshaft will be thrust downwardly with a sudden movement as imparted bythe spring, and will thus jam the electrode back down again into themolten metal caused by the arc during the progress of the rise of theelectrode.

Thiscompletes the cycle of operation, and the parts will remain at restuntil the double throw switch is moved to establish contacts M and Mi'-to start another cycle of operations.

I have not, by virtue of the mode of wiring the apparatus intended toindicate that this is the only electrical arrangement which willaccomplish my object, but merely to illustrate in diagrammatic form asuitable hook-up which I have found satisfactory. The cable to the toolitself will carry the various wires which are needed for connecting upthe several circuits with the control box, which will contain theswitches and coils now noted as C-l to C4, and switches S l to S5. Thetiming is done by the cam or lifting operation which will be settocorrespond. with the rise necessary for the contact ring 24 to bridgethe contacts 23. The amount of welding current in amperage will dependupon the requirements as will be readily worked out for variousoperations within the scope of my new tool.

It is apparent that by making the pitch of the cam or thread that liftsthe tool shaft -a slight one, the electrode ,may be rotated a number oftimes, i. e quite rapidly, during the short burst of arc weldingcurrent, without drawing along 8 arc. Various modifications within thescheme now outlined will-be possible with this tool, andin many respectsthe tool will be valuable, as a bench tool; as well as a portable one.

Penetration is generally defined as the depth of fusion of the weldmetal into thebase metal. This'must not be confused with fusion which isdefined as a mixture only ofthe base and-welding metals- I insure propercontrol of depth ofpenetration by the noveluse of, my rotary electrodedrill which is set to drill to any desired depth in the base metal,thereby creating a clean contact surface in the base metal, upon andwith which the weld metal is later deposited and fused; It is quiteobvious that I can, by thisrotary drill, control. the quality andstrength of the weld by being able to control the penetration. into thebase metal, and by so doing. reduce sizes of members and the cost ofsame.

In centrifugal casting one of the commonly used molds is made withmetal, and. is known as a metal mold. In the casting operation themolten metal is whirled against this mold;

With my rotary drilling electrode I am able to, by choice of electrodesor combinations thereof, create a similar mold in the baseametal;

After drilling through dense material facing or material such as wood,gypsum, transite, glass, etc. to be fastened to theplates, etc., thesecond electrode (the base metal) is-encountered and I am able by choiceof electrode drills to penetrate it to any depth desired, and thus formin the second electrode (base metal) a crater or metal mold. This isalways circular, dueto the rotary motion of the electrode drill, anddepending on the shape of the tip of the electrode drill, the mold maybe a cone or a paraboloid or any variation of these. It may becylindrical with its end a cone or paraboloid, depending-on the shape ofdrill electrode and depth of penetration.

The'crater or metal mold thusformed has many of the characteristics ofthe commonly used plug type weld, only in this case the electrodedrillin part, becomes and remains theplug-aiter being partiallydeposited and fusedintothewalls of the metalmold it drilled, priorto theapplication of the welding current to the electrode, and its subsequentpartial disintegration.

The centrifugal pressureas applied in centrifuga-lcasting, sometimescalled liquid forging, is entirely different from any other forgingpressure applied by any other means. It is selective in its action, thelarger and heavier components being thrown outward toward the peripheryof the metal mold with greater force than the lighter particles.

This centrifugal motion immediately helps to eliminate. slag,non-metallics, and other. impurities from the weld, by flotation due toweight dif, ferentia-l, and the rejection tendency of the bath, with theresultthat they are kept away from the base metal of the metal mold,thus making denser metal, better fusion of the weld metal. and the basemetal. Also gas pockets and porosity are reduced.v

It is also important tonote that thefirst metal from the electrode isdeposited centrifugally at. or flows outward from centrifugal .force,-tothe periphery of' the mold, which is relatively cooler, and which startsthe cooling action atthe outside, progressing toward the center,eliminating stresses setup by; ordinary-methodsv of deposit suchas used;in.- othersportablewelding; tools.

"It is also extremely important to note that in overhead welding, thecentrifugal force applied only by this tool will immediately tend toovercome gravitational pull on the molten metal, oc curring withconventional methods of deposit as used by other portable welding tools,wherein surface tension is the principal means of overcoming gravity.

Rotating speeds used in centrifugal casting are well known and in thiscase the range is from the lowest at which the metal will adhere andfuse to a mold wall of any given shape up to a speed where it will tendto leave the molten pool for reason of too high speed. Any desirablespeed is easily obtained by this setting of the rheostat and number ofrotations by arrangement of the cam.

In its broadest sense the means for moving theshaft axially could beeither mechanical or electrical, and in various forms, and the drawingof the arc could be done without simultaneous rotation of the electrodecarrying shaft. For example, tie rotor of the motor could be directlyconnected to the tool shaft, and itself move axially with the shaft, orthe drive to the tool shaft could be by a thick gear meshing with athinner pinion on the tool shaft.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A tool for arc welding comprising a support, a tool shaft mounted forrotary and sliding movement in the support, means for rotating theshaft, means on the shaft for grasping electroconductively an electrodeto be welded to a work piece, means for applying welding current to thetool shaft, and means operated by the tool shaft for sliding it againstresilient pressure during rotation when the welding current is applied,and then releasing the shaft thereby thrusting the electrode into thework, while simultaneously disconnecting the welding current.

2. The combination of claim 1 in which the means for grasping theelectrode is a clutch of material non-Weldable to the electrode whichholds the electrode in electrical contact with the tool shaft.

3. A tool for arc welding comprising a support, a tool shaft mounted forrotary and sliding movement in the support, a driving electric motor forrotating the tool shaft, means controlled by the operator for applyingrotary motion to the motor selectively through different circuits, oneof which is rheostat controlled, means on the shaft forelectro-conductively grasping an electrode to be welded to a work piece,and means energized by the tool shaft for sliding it against resilientpressure during rotation when welding current is applied to the shaft,means for supplying welding current to the tool shaft when the motor ison the rheostat controlled circuit, and means energized by the shaft foropening all electric circuits and releasing the sliding means therebythrusting the electrode into the work.

4. A tcol for arc welding comprising a rotary shaft and means forsecuring an electrode to be welded into the work to the shaft, cam meanson the shaft, driving connections for rotating the shaft so as to rotatethe electrode into the work permitting that portion thereof connected tothe electrode to be reciprocated, means for engaging the cam means forcausing the shaft to reciprocate through a path defined by said cammeans, operator controlled means for simultaneously applying weldingcurrent to the reciprocating portion of the tool shaft, and causingoperation of the means for engaging the cam, and means operated by thetool shaft as a result of its reciprocatory motion for turning ofi thewelding current and releasing the cam engaging means.

5. A tool for arc welding comprising a rotary shaft and means forsecuring an electrode to be welded into the work to the shaft, cam meanson the shaft, driving connections for rotating the shaft so as to rotatethe electrode into the work permitting that portion thereof connected tothe electrode to be reciprocated, means for engaging the cam means forcausing the shaft to reciprocate through a path defined by said cammeans, operator controlled means for applying welding current to thereciprocating portion of the tool shaft, and simultaneously causing op--eration of the means for engaging the cam, and means operated by thetool shaft as a result of its reciprocatory motion for turning off thewelding current and releasing the cam engaging means, said means forsupplying welding current being arranged to be effective only upon themeans for engaging the cam means entering into engagement with the camsurface.

6. A tool for arc welding comprising means for engaging an electrode andturning it into the Work so as to penetrate an electro-conductive baseto which it is to be welded, means initiated by the operator for raisingthe electrodeby rotary motion when it has penetrated the base to anobserved depth, means for applying welding current to the electrode whenit is being raised by said rotary motion, and means for timing theraising step, terminating the application of welding current when thestep has been completed, and means for then thrusting the electrode intothe base.

7. A tool for arc welding comprising means for engaging an electrode andturning it into the work so as to penetrate an electro-conductive baseto which it is to be Welded, means initiated by the operator for raisingthe electrode by rotary motion when it has penetrated the base to anobserved depth, means for applying Welding current to the electrode whenit is being raised by said rotary motion, and means for timing theraising step, terminating the application of welding current when thestep has been completed, and means for then thrusting the electrode intothe base, the means for turning the electrode into the work comprisingan electric motor, two supply circuits for said motor with controlstherefor and interconnection between the means for supplying the weldingcurrent to the electrode and controls for one of said supply circuits,and a set of electric contacts arranged to be connected by the means forraising the electrode, and adapted to shut off the welding current andterminate the raising step, this arrangement serving to produce thetiming referred to.

8. In an electric welding tool, a tool shaft, cam means on the toolshaft, an electrically controlled abutment to engage the cam means thuscausing the tool shaft to rise, an electric motor for rotating the toolshaft, means for so connecting the tool shaft to the motor that it canrise, resilient means for returning the tool shaft to its position priorto-its rise upon withdrawal of said abutment, means for supplyingwelding current to the tool shaft upon inception of the rising motionthereof, and means for disconnecting the welding current upon completionof the rising motion of the tool shaft.

9. In an electric welding tool, a tool shaft, cam

said abutment, means for supplying weldin'g cur'-' rent to the toolshaft upon inception' of the rising motion thereof, and means 'for'disconnecting the welding current upon completion of the rising motionof the tool shaft, the means for supplying welding current to the toolshaftbeing -ineffective until first causing the abutment to engage thecam means.

10. A portable welding tool comprising amotor and motor shaft, a shaftdriven thereby and arranged for reception ora'n electrode to 'be weldedto rotate the same into the -work,"means for-slidably connectingsaiflshaft with the'motor shaft, means for moving the driven shaft axiallywith respect to the motor shaft, and means oo-incidental with said axialmovement for applying welding current to the said "driven shaft.

11. A portable Weldingtoolcomprisinga motor and motor shaft, a shaftdrivenjthereby andarranged 'for reception "of anelectrode to be weldedto rotate the's'ame intofthe workmeans'f or slidably connecting "saidshaft with the motor shaft, means for moving thedriven shaft ariiallywith respect to the motor shaft, means co-incidental with said axialmovement for ap iying welding current to the said driven shaftfanflIneans'for supplying current to tne-motcr in a plurality of 12 circuits,current being supplied thereby to the motor from a selected one'ofrsaiwcircuits-which is closed simultaneously with a necessary elementof the axial moving means whereby the shaft "is rotateddu'ring itsa'xial movement;

12. A portable electric welding tool'co'mprising means for'detachablyengaging an electrode to be welded, means operator controlled forrotating th said engaging means, :means formoving said engaging meansaxially by virtue of the rotary motion, and interconnected therewithmeans .for applying welding current to :said en'- gaging means wherebysaid electrode may be'one which prepares a crater for :itself in thework comprising the other electrod in the weldingcirwit, and whereby theaxialmovement may create a timing for the drawing of an arc.

ROBERT F. REFERENCES one The following references are "of record in thefile of this patent:

UNII'ED s'rATEs PATENTS

